The response of some physiological indices and yield of wheat (Triticum aestivum L.) cultivars to the application of 6-benzylaminopurine

To investigate the effect of foliar application of cytokinin on gas exchange, remobilization and allocation of photosynthetic materials of wheat cultivars, an experiment was carried out under field conditions. The experimental treatments included foliar application of 6-benzylaminopurine at two levels (0 as control and 50 μM), and six wheat cultivars (Azadi, Karaj 3, Roshan, Falat, Sardari and Yavarus) which as factorial experiment in a randomized complete block design with four replication were studied. The results showed that foliar application of cytokinin increased leaf area index (LAI) and Roshan had the highest leaf area index. Photosynthetic rate of the studied cultivars was also different and the use of cytokinin increased the photosynthetic rate. Foliar application of cytokinin increased the remobilization of Falat, Roshan and Sardari cultivars and decreased Azadi cultivar, but had no significant effect on Karaj 3 and Yavarus cultivars. The effect of cytokinin on the allocation of photosynthetic assimilates to stem, leaf and spike of the studied cultivars was very different, so that with the application of cytokinin, the allocation of photo-assimilates to leaf decreased in Falat and increased in the other cultivars, but in the case of spike, the allocation of photo-assimilates to spike decreased in Roshan cultivar and increased in Karaj 3 and Sardari cultivars, while it did not affect on the other cultivars. In contrast, the allocation of photo-assimilates to stem was reduced about 3.3% by foliar application of cytokinin and Sardari, Yavarus and Roshan cultivars had the highest percentage of the allocation of photo-assimilates to stem. Grain yield of Karaj 3, Yavarus and Sardari cultivars increased by foliar application of cytokinin and the highest and lowest grain yield was observed in the control treatment (no application of cytokinin) in Azadi (5700 kg/ha) and Roshan (3100 kg/ha) cultivars, respectively, while under cytokinin foliar application, Yavaros and Roshan cultivars with 6300 and 3300 kg/ha had the highest and lowest grain yield, respectively. The results of this experiment showed different effects of cytokinin on different traits and wheat cultivars, but to obtain more accurate and complete results, it is suggested to measure the internal cytokinin concentration of wheat cultivars.